d-Methadone for the treatment of psychiatric symptoms

ABSTRACT

The present invention relates to a method of treating psychiatric symptoms in a subject having a NMDA receptor and a NE receptor which includes administering d-methadone, d-methadol, d-alpha-acetylmethadol, l-alpha-acetylmethadol, d-alpha-normethadol, l-alpha-normethadol, pharmaceutically acceptable salts thereof, or mixtures thereof, to the subject under conditions effective for the substance to bind to the NMDA receptor and NE receptor of the subject.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date of U.S. PatentApplication Ser. No. 61/706,178, entitled “d-methadone for the Treatmentof Psychiatric Symptoms,” filed on Sep. 27, 2012, the disclosure ofwhich is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to the treatment of psychiatricconditions, and to compounds for the treatment of psychiatricconditions.

BACKGROUND OF THE INVENTION

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present invention,which are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

Many psychological and psychiatric conditions (some of which can besevere and debilitating) affect individuals. These conditions includedepression, anxiety disorders, and fatigue. Depression is a mentaldisorder characterized by episodes of all-encompassing low moodaccompanied by low self-esteem and loss of interest or pleasure innormally enjoyable activities. The term “depression” may denote thissyndrome, but may refer to other mood disorders or to lower mood stateslacking clinical significance. Major depressive disorder is aclinically-diagnosed and disabling condition that adversely affects aperson's family, work, and/or school life, sleeping and eating habits,general health, and can lead to self-harm.

Presently, individuals suffering from depression are often treated withantidepressant medication. The treatment of depression wasrevolutionized in the 1950s by the discovery of monoamine oxidaseinhibitors (MAOIs) and tricyclic antidepressants (TCAs). This wasfollowed in the 1980s by the advent of the first selective serotoninreuptake inhibitor (SSRI).

Many antidepressant medications work via mechanisms that ultimatelyincrease the amount and availability of neurotransmitters for signalingbetween nerve cells. In the brain, messages are passed between two nervecells via a chemical synapse, a small gap between the cells. Thepresynaptic cell releases neurotransmitters (e.g., serotonin,norepinephrine, etc.) into the synapse. The neurotransmitters are thenrecognized by receptors on the surface of the postsynaptic cell (i.e.,the recipient cell). Following the completion of this process, the largemajority of the neurotransmitters are released from the receptors andtaken up by monoamine transporters into the presynaptic cell (a processcalled reuptake). MAOIs, TCAs, and SSRIs function by influencing thisprocess.

As is known to those of ordinary skill in the art, MAOIs are chemicalswhich inhibit the activity of the monoamine oxidase enzyme family, thuspreventing the breakdown of monoamine neurotransmitters and increasingtheir availability. In the past, MAOIs were prescribed for thoseresistant to tricyclic antidepressant therapy. However, because ofpotentially problematic dietary and drug interactions, MAOIs havehistorically been used only when other classes of antidepressant drugs(e.g., selective serotonin reuptake inhibitors and tricyclicantidepressants) have failed.

Tricyclic antidepressants (TCAs) are heterocyclic chemical compounds,the majority of which act primarily as serotonin-norepinephrine reuptakeinhibitors (SNRIs) by blocking the serotonin transporter and thenorepinephrine (NE) transporter, respectively. This results in anelevation of the synaptic concentrations of these neurotransmitters, andtherefore an enhancement of neurotransmission.

In recent times, TCAs have been largely replaced in clinical use bynewer antidepressants such as the selective serotonin reuptakeinhibitors (SSRIs), which typically have more favorable side-effectsprofiles.

Selective serotonin re-uptake inhibitors (SSRIs)—such as Prozac®,Zoloft®, and Paxil®—are a class of compounds that increase theextracellular level of the neurotransmitter serotonin by inhibiting itsreuptake into the presynaptic cell, increasing the level of serotonin inthe synaptic cleft available to bind to the postsynaptic receptor. As aresult, the serotonin stays in the synaptic gap longer than it normallywould, and may repeatedly stimulate the receptors of the recipient cell.

Apart from MAOIs, TCAs, and SSRIs, additional antidepressant medicationshave been developed. However, since the advent of SSRIs in the 1980s,newer medications are largely “me too” drugs that exert their primarybiochemical effects by increasing the intra-synaptic levels ofmonoamines.

Typically medications such as MAOIs, TCAs, and SSRIs take weeks toachieve their full effects. For example, high serotonin levels (due tothe effects of some antidepressant medications, such as SSRIs) will notonly activate the postsynaptic receptors, but also presynapticautoreceptors, which serve as a feedback sensor for the cell. Activationof the autoreceptors (by agonists like serotonin) triggers a reductionof serotonin production. The resulting serotonin deficiency persists forsome time, although the body gradually adapts to this situation bylowering the sensitivity of the autoreceptors.

These slow neurophysiological adaptations of the brain tissue are thereason why several weeks of continuous SSRI use is generally necessaryfor the antidepressant effect to become fully manifested, and whyincreased anxiety is a common side effect in the first few days or weeksof use.

Unfortunately, during this lag time, patients continue to suffer fromsymptoms of depression. Indeed, this lag period in onset of action oftraditional antidepressants (of up to several weeks) results in risk ofself-harm as well as harm to the patients' personal and professionallives, especially in the first days after starting antidepressanttreatment. Furthermore not all patients respond to drugs that increasethe intra-synaptic levels of monoamines (such as serotonin).

SUMMARY OF THE INVENTION

Certain exemplary aspects of the invention are set forth below. Itshould be understood that these aspects are presented merely to providethe reader with a brief summary of certain forms the invention mighttake and that these aspects are not intended to limit the scope of theinvention. Indeed, the invention may encompass a variety of aspects thatmay not be explicitly set forth below.

As described above, current medications for depression suffer severaldrawbacks (e.g., taking long periods of time to achieve their fulleffects). Furthermore, available antidepressants are ineffective in arelatively high percentage of depressed patients. Furthermore, severalpsychiatric symptoms, in addition to depression, such as anxietydisorders, fatigue, psychological symptoms associated with withdrawalfrom various substances, are inadequately treated by the availablepsychiatric drugs, including anxiolytics, neuroleptics, antidepressants,mood stabilizers. And, although medications have been developed and usedto treat conditions such as depression, not all patients respond todrugs that increase the intra-synaptic levels of monoamines.

In view of the drawbacks listed above, pharmacological strategies that(1) have rapid onset of antidepressant effects (within hours or even afew days), (2) are sustained, would have an enormous impact on publichealth, and (3) are effective in patients refractory to availabletreatments.

Various aspects of the present invention are based on the discovery bythe present inventors that such patients may respond to NMDA receptorantagonists (substances that bind the N-methyl-D-aspartate receptor), ora drug like d-methadone, which combines NMDA receptor antagonisms withinhibition of NE re-uptake, alone or in combination with standardtherapy. Previously, those of ordinary skill in the art have notconsidered NMDA receptor antagonists such as d-methadone to be candidatecompounds for treatment of psychiatric conditions for many reasons,including (but not limited to) the connotation of methadone (and thusd-methadone) as an addictive opioid drug. Furthermore, the lack ofunderstanding about of the NMDA activity of d-methadone combined withits lack of substantial opioid activity, as shown by Inturrisi [SeeGorman, A. L., Elliott, K. J. and Inturrisi, C. E., The d- and l-isomersof methadone bind to the non-competitive sit on the N-methyl-D-aspartate(NMDA) receptor in rat forebrain and spinal cord, NerurosciLett, 223(1997) 5-8; Shimoyama, N. et. al, “d-methadone Is Antinociceptive in theRat Formalin Test,” J Pharma and ExperTherap, 293 (1997) pp. 648-652;Davis, A. M. and Inturrisi, C. E., “d-methadone Blocks MorphineTolerance and N-Methyl-D-Aspartate-Induced Hyperalgesia,” J Pharma andExperTherap, 289 (1999) pp. 1048-1053. incorporated by reference hereinin its entirety]. Further, even though medications such asantidepressants are still an area of major medical need, Forbes noted inMay, 2102 that companies like Novartis, GSK, and AstraZeneca had ceasedtheir neuroscience research efforts and other large pharmaceuticalcompanies such as Merck, Pfizer and Sanofi had drastically scaled backtheir research, due to reasons including high placebo success rates.(See LaMattina, John, “Will Lundbeck's New Antidepressant Be a Major NewDrug?” Forbes online, Pharma & Healthcare, May 22, 2012.)

Thus, one aspect of the present invention provides a method of treatingpsychological and psychiatric symptoms in a subject having a NMDAreceptor. The method includes administering a NMDA receptor antagonistsubstance (such as d-methadone, d-methadol, d-alpha-acetylmethadol,l-alpha-acetylmethadol, d-alpha-normethadol, l-alpha-normethadol,pharmaceutically acceptable salts thereof, or mixtures thereof) to asubject under conditions effective for the substance to bind to the NMDAreceptor of the subject and thereby relieve the subject frompsychological symptoms such as depression, anxiety, fatigue, moodinstability including pseudo-bulbar affect. The substance may beisolated from its enantiomer or synthesized de novo.

A second aspect of the present invention provides a method of treatingpsychological and psychiatric symptoms in a subject having a NEreceptor. The method includes administering a substance (such asd-methadone, d-methadol, d-alpha-acetylmethadol, l-alpha-acetylmethadol,d-alpha-normethadol, l-alpha-normethadol, pharmaceutically acceptablesalts thereof, or mixtures thereof) to a subject under conditionseffective for the substance to bind to the NE receptor of the subjectand thereby relieve the subject from psychological symptoms such asdepression, anxiety, fatigue, mood instability including pseudo-bulbaraffect. The substance may be isolated from its enantiomer or synthesizedde novo.

Thus, various aspects of the present invention include the use ofd-methadone for the treatment of depression. They also include the useof d-methadone for the acute/rapid treatment of depression. d-methadonemay be used alone for the acute and chronic treatment of depression, orin combination with other antidepressants and or other NMDA antagonists.

Another aspect of the present invention includes the use of d-methadonefor the treatment of anxiety, fatigue, or mood instability (includingpseudobulbar affect).

Another aspect of the present invention includes the use of d-methadonefor the treatment of psychological symptoms (depression, moodinstability, pseudobulbar affect, dysphoria, anxiety, fatigue andothers) associated with chronic pain, including cancer pain.

Another aspect of the present invention includes the use of d-methadonefor the treatment of psychological symptoms (depression, moodinstability, pseudobulbar affect, dysphoria, anxiety, fatigue andothers) associated with cancer.

Another aspect of the present invention includes the use of d-methadonefor the treatment of psychological symptoms (depression, moodinstability, pseudobulbar affect, dysphoria, anxiety, fatigue andothers) associated with opioid therapy.

Another aspect of the present invention includes the use of d-methadonefor the treatment of psychological symptoms (including depression, moodinstability, pseudobulbar affect, dysphoria, anxiety, fatigue andothers) associated with withdrawal from various substances, includingalcohol, tobacco, opioids, antidepressants, benzodiazepines, alone or incombination with nicotine or with antidepressants, anxiolytics,antipsychotics, mood stabilizers, lithium, stimulants, NMDA antagonists,and/or analgesics.

d-methadone may be clinically useful for some or all of the aboveindications alone or in combination with antidepressants, anxiolytics,antipsychotics, mood stabilizers, lithium, stimulants, NMDA antagonists,and analgesics.

Another aspect of the present invention includes the use of d-methadoneorally or intravenously, for the acute treatment of depression inpatients at the start of antidepressant therapy for a more rapidtherapeutic onset: available antidepressants require several weeks forthe onset of effects while d-methadone may be effective more rapidly,therefore avoiding or reducing the increased risk of suicide seen inpatients during the first few weeks of treatment with the availableantidepressants.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,together with the general description of the invention given above andthe detailed description of the embodiments given below, serve toexplain the principles of the present invention.

The FIGURE shows the structure of d-methadone.

DETAILED DESCRIPTION

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, all features of an actual implementation may not bedescribed in the specification. It should be appreciated that in thedevelopment of any such actual implementation, as in any engineering ordesign project, numerous implementation-specific decisions must be madeto achieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

As described above, current medications suffer several drawbacks (suchas taking long periods of time to achieve their full effects).Furthermore, available antidepressants are ineffective in a relativelyhigh percentage of depressed patients. Furthermore, several psychiatricsymptoms, in addition to depression, such as anxiety disorders, fatigue,psychological symptoms associated with withdrawal from varioussubstances, are inadequately treated by the available psychiatric drugs,including anxiolytics, neuroleptics, antidepressants, mood stabilizers.And, although medications have been developed and used to treatdepression, not all patients respond to drugs that increase theintra-synaptic levels of monoamines.

However, the present inventors have discovered that such patients mayinstead respond to NMDA antagonists, or a drug like d-methadone, whichcombines NMDA antagonisms with inhibition of NE re-uptake, alone or incombination with standard therapy.

Thus, one aspect of the present invention provides a method of treatingpsychological and psychiatric symptoms in a subject having a NMDAreceptor. The method includes administering a NMDA-receptor antagonistsubstance (such as d-methadone, d-methadol, d-alpha-acetylmethadol,l-alpha-acetylmethadol, d-alpha-normethadol, l-alpha-normethadol,pharmaceutically acceptable salts thereof, or mixtures thereof) to asubject under conditions effective for the substance to bind to the NMDAreceptor of the subject and thereby relieve the subject frompsychological symptoms such as depression, anxiety, fatigue, moodinstability including pseudo-bulbar affect. The substance may beisolated from its enantiomer or synthetized de novo.

As described above, NMDA receptor antagonists are a class of anestheticsthat antagonize, or inhibit the action of, the NMDA receptor. The NMDAreceptor, a glutamate receptor, is the predominant molecular device forcontrolling synaptic plasticity and memory function and allows for thetransfer of electrical signals between neurons in the brain and in thespinal column. For electrical signals to pass, the NMDA receptor must beopen. To remain open (activated), glutamate and glycine must bind to theNMDA receptor.

Chemicals that deactivate the NMDA receptor are called antagonists. NMDAreceptor antagonists fall into four categories: (1) competitiveantagonists, which bind to and block the binding site of theneurotransmitter glutamate; (2) glycine antagonists, which bind to andblock the glycine site; (3) noncompetitive antagonists, which inhibitNMDA receptors by binding to allosteric sites; and (4) uncompetitiveantagonists, which block the ion channel by binding to a site within it.Several synthetic opioids function as NMDA receptor-antagonists, such asmethadone, meperidine, dextropropoxyphene, tramadol, levorphanol, andketobemidone.

Furthermore, (1) NMDA receptors are adaptively altered in circumscribedcentral nervous system (CNS) areas following chronic antidepressant (AD)therapy, and (2) behavioral studies show AD-like actions of severalfunctional NMDA antagonists. Neurochemical studies have shown thatchronic administration of NMDA antagonists to rodents leads to a downregulation of cortical β-adrenoceptors. Chronic administration of ADs tomice produces adaptive changes in radioligand binding to NMDA receptors.Studies with imipramine, electroconvulsive shock (ECS), and citalopramshow that these changes develop slowly and persist for some time aftertreatment cessation. Changes due to these drugs are dose dependent andrestricted to the cerebral cortex. [For the above, see Skolnick, P.;Layer, R. T.; Popik, P.; Nowak, G.; et al Adaptation ofN-methyl-D-aspartate (NMDA) receptors following antidepressanttreatment: Implications for the pharmacotherapy of depression.Pharmacopsychiatry, Vol 29(1), January 1996, 23-26, incorporated byreference herein in its entirety.] Further, radioligand-binding to theNMDA receptor is altered in frontal cortex of suicide victims. And so,the present inventors' position is that NMDA receptors may be involvedin the pathophysiology of depression. Thus, the present inventors havedetermined that a drug like d-methadone, which combines NMDAantagonistic activity and NE re-uptake inhibition, may offer uniqueadvantages for the treatment of psychiatric symptoms, includingdepression.

A second aspect of the present invention provides a method of treatingpsychological and psychiatric symptoms in a subject having a NEreceptor. The method includes administering a substance such asd-methadone, d-methadol, d-alpha-acetylmethadol, l-alpha-acetylmethadol,d-alpha-normethadol, l-alpha-normethadol, pharmaceutically acceptablesalts thereof, or mixtures thereof to a subject under conditionseffective for the substance to bind to the NE receptor of the subjectand thereby relieve the subject from psychological symptoms such asdepression, anxiety, fatigue, mood instability including pseudo-bulbaraffect. The substance may be isolated from its enantiomer or synthetizedde novo.

The NE receptor is an adrenergic receptor. As is known to those ofordinary skill in the art, the adrenergic receptors (or adrenoceptors)are a class of G protein-coupled receptors that are targets of thecatecholamines, especially norepinephrine and epinephrine. Many cellspossess these receptors, and the binding of a catecholamine to thereceptor will generally stimulate the sympathetic nervous system. Thus,various aspects of the present invention include the use of d-methadonefor the treatment of depression. They also include the use ofd-methadone for the acute/rapid treatment of depression. d-methadone maybe used alone for the acute and chronic treatment of depression, or incombination with other antidepressants and or other NMDA antagonists.

Another aspect of the present invention includes the use of d-methadonefor the treatment of psychological symptoms (depression, moodinstability, pseudobulbar affect, dysphoria, anxiety, fatigue andothers) associated with cancer.

Another aspect of the present invention includes the use of d-methadonefor the treatment of psychological symptoms (depression, moodinstability, pseudobulbar affect, dysphoria, anxiety, fatigue andothers) associated with opioid therapy.

Another aspect of the present invention includes the use of d-methadonefor the treatment of psychological symptoms (including depression, moodinstability, pseudobulbar affect, dysphoria, anxiety, fatigue andothers) associated with withdrawal from various substances, includingalcohol, tobacco, opioids, antidepressants, benzodiazepines, alone or incombination with nicotine or with antidepressants, anxiolytics,antipsychotics, mood stabilizers, lithium, stimulants, NMDA antagonists,analgesics.

d-methadone may be clinically useful for some or all of the aboveindications alone or in combination with antidepressants, anxiolytics,antipsychotics, mood stabilizers, lithium, stimulants, NMDA antagonists,and analgesics.

Another aspect of the present invention includes the use of d-methadoneorally or intravenously, for the acute treatment of depression inpatients at the start of antidepressant therapy for a more rapidtherapeutic onset: available antidepressants require several weeks forthe onset of effects while d-methadone may be effective more rapidly,therefore avoiding or reducing the increased risk of suicide seen inpatients during the first few weeks of treatment with the availableantidepressants.

Another aspect of the present invention includes the use of d-methadonefor the treatment of psychological symptoms at total daily dosages of 1mg to 5000 mg.

Methadone is a synthetic opioid. It is used medically as an analgesicand a maintenance anti-addictive and reductive preparation for use bypatients with opioid dependency. Because it is an acyclic analog ofmorphine, methadone acts on the same opioid receptors and thus has manyof the same effects. Methadone is also used in managing severe chronicpain, owing to its long duration of action, extremely powerful effects,and very low cost. The term d-methadone indicates the dextrorotatoryoptical isomer salt of methadone, (+)-methadone HCL.

Methadone acts by binding to the p-opioid receptor, but also has someaffinity for the NMDA receptor. d-methadone is an NMDA antagonist and NEreuptake inhibitor with very weak or no opioid activity.

As described above, aspects of the present invention are directed toadministering substances to a subject to affect the presence ofneurotransmitters (by blocking receptors and/or reuptake ofneurotransmitters). Thus, the NMDA receptor is capable of biologicalaction, and the administering of the substance in the present inventionis effective to block the biological action of the NMDA receptor. TheNMDA receptor may be located in the central nervous system of thesubject.

Alternatively, or additionally, the subject may have an NE receptor thatis capable of biological action, and the administering of the substancein the present invention is effective to inhibit the NE reuptake at theNE receptor. The NE receptor may be located in the central nervoussystem of the subject.

In another embodiment of the present invention, the method may includeadministering more than one substance to a subject. For example, themethod may further comprise administering a psychiatric drug to thesubject in combination with the administering of d-methadone. In variousembodiments, this psychiatric drug may be chosen from an antidepressant,an anxiolytic, a CNS stimulant, a neuroleptic, an opioid, nicotine, oranother NMDA antagonist.

In various aspects and embodiments of the present invention, theadministering of the psychiatric drug and the d-methadone is performedorally, nasally, rectally, trans-dermally, parenterally, or topically.

In various aspects and embodiments, the present invention may furthercomprise administering at least one d-isomer of an analog of d-methadonein combination with the administering of d-methadone.

As described above, (1) NMDA receptors are adaptively altered incircumscribed CNS areas following chronic antidepressant (AD) therapy,and (2) behavioral studies show AD-like actions of several functionalNMDA antagonists. Neurochemical studies have shown that chronicadministration of NMDA antagonists to rodents leads to a down regulationof cortical β-adrenoceptors. Chronic administration of ADs to miceproduces adaptive changes in radioligand binding to NMDA receptors.Studies with imipramine, electroconvulsive shock (ECS), and citalopramshow that these changes develop slowly and persist for some time aftertreatment cessation. Changes due to these drugs are dose dependent andrestricted to the cerebral cortex. [See Skolnick, P.; Layer, R. T.;Popik, P.; Nowak, G.; et al Adaptation of N-methyl-D-aspartate (NMDA)receptors following antidepressant treatment: Implications for thepharmacotherapy of depression. Pharmacopsychiatry, Vol 29(1), January1996, 23-26, incorporated by reference herein in its entirety.] Further,radioligand-binding to the NMDA receptor is altered in frontal cortex ofsuicide victims. Thus, NMDA receptors may be involved in thepathophysiology of depression.

NMDA receptor antagonists have anti-depressant effects in many animalmodels of depression, including the application of inescapablestressors, forced-swim, and tail suspension-induced immobility tests; inlearned helplessness models of depression; and in animals exposed to achronic mild stress procedure. A single dose of the NMDA antagonistketamine hydrochloride in male Wistar rats interferes with the inductionof behavioral despair for up to 10 days after its administration.Additionally, repeated administration of different classes ofantidepressants—in a time frame consistent with the delayed therapeuticeffects—brings about alterations in the expression of NMDA subunitmessenger RNA and radioligand binding to these receptors in regions ofthe brain implicated in the pathophysiology of depression. (See TrullasR, Skolnick P. Functional antagonists at the NMDA receptor complexexhibit antidepressant actions. Eur J Pharmacol. 1990; 185:1-10; YilmazA, Schulz D, Aksoy A, Canbeyli R. Prolonged effect of an anesthetic doseof ketamine on behavioral despair. PharmacolBiochemBehay. 2002;71:341-344; and Boyer P A, Skolnick P, Fossom L H. Chronicadministration of imipramine and cita-lopram alters the expression ofNMDA receptor subunit mRNAs in mouse brain: a quantitative in situhybridization study. J MolNeurosci. 1998; 10:219-233, incorporated byreference herein in their entireties.)

As is known to those of ordinary skill in the art, ketamine is a drugused in human and veterinary medicine, primarily for the induction andmaintenance of general anesthesia, usually in combination with asedative. Other uses include sedation in intensive care, analgesia(particularly in emergency medicine), and treatment of bronchospasm.Ketamine has a wide range of effects in humans, including analgesia,anesthesia, hallucinations, elevated blood pressure, andbronchodilation.

Pharmacologically, ketamine is classified as an NMDA receptorantagonist. At high, fully anesthetic level doses, ketamine has alsobeen found to bind to μ-opioid receptors type 2 in cultured humanneuroblastoma cells—however, without agonist activity—and to sigmareceptors in rats. Also, ketamine interacts with muscarinic receptors,descending monoaminergic pain pathways and voltage-gated calciumchannels.

Several lines of evidence from studies also suggest that dysfunction ofthe glutamatergic system may play an important role in thepathophysiology of depression. As is known to those skilled in the art,glutamic acid is one of the 20-22 proteinogenic amino acids, and thecarboxylate anions and salts of glutamic acid are known as glutamates.In neuroscience, glutamate is an important neurotransmitter. The NMDAreceptor is a glutamate receptor. Nerve impulses trigger release ofglutamate from the pre-synaptic cell. In the opposing post-synapticcell, glutamate receptors, such as the NMDA receptor, bind glutamate andare activated. In clinical trials, the glutamatergic modulatorslamotrigine and riluzole (both inhibitors of glutamate release) werefound to have antidepressant properties. Further, a recent study bySanacora et al showed glutamate levels in the occipital cortex to besignificantly elevated in 29 medication-free subjects with unipolarmajor depression as compared with 28 age- and sex-matched healthycontrols (Sanacora G, Gueorguieva R et al., Subtype-specific alterationsof gamma-aminobutyric acid and glutamate in patients with majordepression., Arch Gen Psychiatry. 2004; 61:705-713, incorporated byreference herein in its entirety). Together, these data support thehypothesis of regional alterations in glutamatergic signaling in mooddisorders.

Based on the preclinical and preliminary clinical studies, NMDA receptorcomplex may mediate the delayed therapeutic effects of traditionalmonoaminergic-based antidepressants and, furthermore, that directlytargeting the NMDA receptor could bring about rapid antidepressanteffects. Indeed, first in a preliminary study of 8 subjects with majordepression, it was reported that a single dose of the noncompetitiveNMDA receptor antagonist ketamine resulted in a rapid and short-livedantidepressant effect. (See Berman R M, Cappiello A, Anand A, Oren D A,Heninger G R, Charney D S, Krystal J H. Antidepressant effects ofketamine in depressed patients. Biol Psychiatry. 2000; 47:351-354,incorporated by reference herein in its entirety.)

This first trial was followed by a second trial (a double-blind trial)in a relatively refractory population. This second trial confirmed arapid (110 minutes), and relatively sustained (1 week) antidepressantresponse to a single dose of the NMDA antagonist ketamine. (See Zarate,C A Jr, Singh J B et al., Randomized Trial of an N-methyl-D-aspartateAntagonist in Treatment-Resistant Major Depression. Arch Gen Psy 2006;63: 856-864, incorporated by reference herein in its entirety).

However, as noted above, there are many drawbacks to current NMDAreceptor antagonists, such as ketamine. However, the present inventorshave discovered that a compound such as d-methadone may not suffer fromthese drawbacks. As observed by Manfredi (one of the present inventors),patients with severe cancer pain unrelieved by high doses of opioidswere achieving relief with very low doses of methadone, less than onetwentieth of the expected equianalgesic opioid dose (Manfredi P L,Borsook D, Chandler S W, Payne R. Intravenous methadone for cancer painunrelieved by morphine and hydromorphone. Pain 1997; 70: 99-101,incorporated by reference herein in its entirety). The NMDA antagonisticactivity of d-methadone directly affects pain pathways, as shown byInturrisi (one of the present inventors) [See Gorman, A. L., Elliott, K.J. and Inturrisi, C. E., The d- and l-isomers of methadone bind to thenon-competitive sit on the N-methyl-D-aspartate (NMDA) receptor in ratforebrain and spinal cord, NerurosciLett, 223 (1997) 5-8, incorporatedby reference herein in its entirety], but as shown by the inventors inthe phase I study described below, d-methadone may also have an effecton pain by directly affecting psychiatric symptoms. Manfredi alsoobserved that patients with history of opioid abuse responded better tomethadone compared to other opioids (Manfredi P L, Gonzales G R,Cheville A L, Kornick C and Payne R. Methadone analgesia in cancer painpatients on chronic methadone maintenance therapy. J Pain Sympt Manag.February 2001; 21(2):169-174, incorporated by reference herein in itsentirety). This may be due to improvement in analgesia but alsoimprovement of the psychiatric symptoms that often affect these patientsand influence the perception of pain intensity. Furthermore, the severepain escalation noted by Manfredi in patients when methadone wassubstituted by other opioids may be due to untreated anxiety from suddenlack of NMDA block (Moryl N, Santiago-Palma J, M D, Kornick C, Derby S,Fischberg D, Payne R and Manfredi P. Pitfalls of opioid rotation:substituting another opioid for methadone in the treatment of cancerpain. Pain 2002; 96 (3): 325-328, incorporated by reference herein inits entirety).

In addition, d-methadone has been shown to be safe in clinical studiesdating back to the 1950s, and when used together with its isomer asracemic methadone. This safety was shown at doses much higher than thoseexpected to be effective for pain. Furthermore, d-methadone is notaddictive and was not recognized as an opioid by heroin addicts and didnot work as a substitute for opioids in this patient population.However, the fact that racemic methadone is successfully used for thetreatment of addiction may be in part due to the activity of d-methadoneat the NMDA receptor. In other words, d-methadone does not work as anopioid substitute the way racemic methadone, which is a potent opioid,does, but d-methadone may be effective for the treatment of thepsychological symptoms that commonly outlive and persist beyond theacute opioid withdrawal phase. Often patients detoxified from opioids,after the opioid withdrawal syndrome is over, are treated withantidepressant, antianxiety, and mood stabilizing drugs. Based on thephase I-II study findings described below, the clinical observations ofthe use of methadone from Manfredi cited above [Manfredi P L, Gonzales GR, Cheville A L, Kornick C and Payne R. Methadone analgesia in cancerpain patients on chronic methadone maintenance therapy. J Pain SymptManag. February 2001; 21(2):169-174, incorporated by reference herein inits entirety], and the experimental studies from Inturrisi, also citedabove (Gorman, A. L., Elliott, K. J. and Inturrisi, C. E., The d- andl-isomers of methadone bind to the non-competitive sit on theN-methyl-D-aspartate (NMDA) receptor in rat forebrain and spinal cord,NerurosciLett, 223 (1997) 5-8, incorporated by reference herein in itsentirety), d-methadone may be more effective than conventionalpsychiatric drugs in treating depression anxiety and other psychiatricsymptoms, including the sub-acute and chronic psychiatric symptoms thatfollow or are concomitant to stressful events such as pain, cancer,opioid treatment and opioid withdrawal.

In the phase I study developed by the present inventors and performed byinvestigators (Drs. Natalie Moryl, Dana Tarcatu, and Eugenie Obbens) atMemorial Sloan-Kettering Cancer Center, New York, N.Y. (described ingreater detail below) in very sick patients with severe cancer pain,d-methadone was not only well tolerated but it was liked by the patientswho recognized it as an effective analgesic.

Thus, based on these results, the present inventors have determined thatd-methadone is not only safe but would prove itself analgesic (in aphase II study). The most suitable study would likely be in patientswith diabetic neuropathy, similarly to what has been done with othernon-opioid analgesics. This pathway to approval would likely beconducive to a widespread use in most pain syndromes: clinicianstreating patients with cancer pain and neuropathic pain in addition tothose treating non-malignant chronic pain are waiting for safe,non-addictive analgesics, to be used either alone or in combination withopioids and other analgesics.

The NMDA receptor antagonists have received much attention fromscientists and industry because of their effects on a crucial chronicpain circuit. Unfortunately the designer high affinity drugs such asMK-801 are not safe. The NMDA antagonists on the market have knownproblems. Ketamine causes hallucinations, dextrometorphan has a veryshort half life and memantine a very long one which depends heavily onrenal excretion. Also the effects of dextrometorphan and memantine maybe too weak to produce analgesia.

On the other hand, d-methadone is proven to be safe and, as determinedby the present inventors, has the optimal affinity to be effective foranalgesia. Its half life and liver metabolism are other advantages.

In addition to NMDA antagonistic activity, d-methadone is a weakinhibitor of NE reuptake. Codd E E, Shank R P, et al. Serotonin andNorepinephrine activity of centrally acting analgesics: Structuraldeterminants and role in antinociception. IPET 1995; 274 (3)1263-1269(incorporated by reference herein in its entirety). Thus, this may alsocontribute to alleviate psychiatric symptoms, especially depression.

Additionally, Krystal et al. [Krystal J H, D'Souza D C, Petrakis I L,Belger A, Berman R M, Charney D S, Abi-Saab W, Madonick S., NMDAagonists and antagonists as probes of glutamatergic dysfunction andpharmacotherapies in neuropsychiatric disorders., Harv Rev Psychiatry.1999 September-October; 7(3):125-43 (incorporated by reference herein inits entirety)] suggest that the degree to which NMDA antagonists produceeffects within a given domain is related to the extent of theenvironmental stimulation within that domain. This particular mode ofaction may be important when the NMDA receptors of patients areabnormally stimulated as may happen with depression, stress provokingsituations and anxiety disorders, including those occurring withsubstance withdrawal.

EXAMPLE

The following describes the phase I study (referenced above) ofd-methadone administered to patients with chronic pain. In particular,investigators at Memorial Sloan-Kettering Cancer Center (of New York,N.Y.) performed a study of d-methadone administered to patients withchronic pain at a dose of 40 mg every 12 hours for 12 days. Thefollowing details the results of the phase I portion of that study.

Protocol Summary

The study was a Phase I open label study of d-methadone in patients withchronic pain and multiple co-morbitities. Seven out of eight patientscompleting the study had advanced cancer. The patients were taking anaverage of 5 different drugs. And all patients had persistent paindespite strong opioids and other analgesics titrated to effect. Theobjective of the study was to determine if 40 mg of d-methadoneadministered every 12 hours to chronically ill patients with chronicpain is safe and well tolerated.

The background and rationale for the study was as follows: (1) Toleranceto opioid analgesia necessitates dose escalation, which can result in anincrease in adverse effects; (2) NMDA receptor antagonists attenuatechronic pain, especially neuropathic pain; and (3) NMDA receptorantagonists attenuate and reverse opioid analgesic tolerance [Inturrisi,C. E. “Opioid Analgesic Therapy in Cancer Pain,” Advances in PainResearch and Therapy, (K. M. Foley, J. J. Bonica, and V. Ventafridda,Eds.) pp. 133-154, incorporated by reference herein in its entirety].

Both d-methadone and 1-methadone are NMDA antagonists. Only l-methadonebinds to opioid receptors. Treatment with d-methadone results in NMDAantagonism without opioid receptor activity. [See Gorman, A. L.,Elliott, K. J. and Inturrisi, C. E., The d- and l-isomers of methadonebind to the non-competitive sit on the N-methyl-D-aspartate (NMDA)receptor in rat forebrain and spinal cord, Nerurosci Lett, 223 (1997)5-8, incorporated by reference herein in its entirety.]

Thus, d-methadone could be used as an independent non-opioid analgesicfor patients with chronic pain. Further, d-methadone could be added toopioids to prevent tolerance and dose escalation.

Criteria for Patient Eligibility

In order to be considered eligible for the study, individuals had to:(1) be experiencing chronic pain, and had to have experienced paingreater than or equal to 3 on a 0-10 visual analogue scale (VAS) in theprevious 24 hours; (2) be 18 years of age or older; (3) have a KPS(Karnofsky Performance Status) of greater than or equal to 80; (4) notbe pregnant; and (5) have a responsible companion living with themduring the study (12 days).

Any of the following would serve to exclude an individual from thestudy: (1) a known hypersensitivity to methadone; (2) if the patient wastaking methadone or previous methadone treatment within one month ofenrollment (3) any changes in the dose of the following medicationswithin 2 weeks of study enrollment: Abacavir, Benzodiazepines,Carbamazepine, Efavirnez, Fluconazole, Fluvoxamine, Neltrexone,Nelfinavir, Nevirapine, Phenytoin, Risperidone, Ritonavir, AZT, St.John's Wort; or (4) a baseline QTc>0.440/year.

Once individuals were selected, they were given a pretreatmentexamination, to diagnose and determine: (1) pain diagnosis, (2)analgesic regimen and concurrent pharmacological therapies, (3) existingside effects, (4) the Symptom Assessment Sheet-BaselineEKG, (5)mini-mental state examination (MMSE), and (6) renal and liver functiontests.

305 individuals were screened for participation in the study. 295patients were excluded for not meeting the inclusion criteria, or otherreasons (e.g., did not choose to participate). 10 patients signed aconsent to participate in the study. However, one patient becameineligible before the study began, and one patient was removed from thestudy based on that patient's request. 8 patients completed the study.

Methods

Administration of d-methadone was at 40 mg PO q12 hr for 12 days.Patients visited the clinic on days 1, 8, and 12. The patients also kepta daily diary (concerning side effects and analgesia). Doctors involvedin the study also kept a daily diary (based on daily phone interviewswith the patients). Serum d-methadone level for each patient wasmeasured 6 hours after the morning dose on day 12. EKGs of each patientwere taken on days 1, 8, and 12. A MMSE was given to each patient ondays 1 and 12. And a Global Assessment for pain and Global Assessmentfor mood was determined for each patient on day 12.

Results

Results are shown in Tables 1-3 (below) and the discussion thereafter.

TABLE 1 Results - Demographics Patient # Race Gender Diagnosis Paindiagnosis 01 WNH f meningioma back pain due to metastatic disease 56 WNHm renal cell back pain/ carcinoma postthoracotomy pain 117 WNH mlymphoma back pain due to spinal stenosis, neuropathy 224 WH f lymphomaneck pain/shoulder pain after lymphoma resection 258 WNH m acuteleukemia hip pain due to avascular necrosis 300 BNH f breast cancerchemotherapy induced neuropathy 301 WNH m degenerative jointdegenerative joint disease disease 302 WNH f thyroid cancerarthralgia/neuropathy after chemotherapy 303 WNH f breast cancerpostmastectomy pain, carpal tunnel syndrome 305 WH f cystadenocarcinomachest pain due to chest wall metastases

TABLE 2 Results - Edmonton Symptom Assessment Scale Administered on day1 (baseline) and day 12 Well-being Pain Tiredness Anxiety Drowsiness(10-the worst) Patient Baseline Day 12 Baseline Day 12 Baseline Day 12Baseline Day 12 Baseline Day 12 1 4 5 4 5 4 3 2 0 5 0 56 7 2 9 4 1 4 0 10 2 117 5 5 8 7 0 0 0 0 0 0 258 1 5 8 6 0 0 3 3 4 3 301 3 3 0 0 3 1 0 06 1 302 6 9 5 5 0 0 2 5 2 1 303 4 4 6 0 5 2 0 0 6 9 305 3 0 7 2 7 2 0 110 7 4.1 4.1 5.9 3.6 2.5 1.5 0.9 1.3 4.1 2.9

TABLE 3 Results - Summary and attribution of adverse events documentedin the diaries AE according to CTCAE v3.0 for 8 patients that completedthe study and 1 patient who was removed from the study CTCAE v3.0 AE #of patients Grade (1-5) Attribution Neurology Somnolence 2 2 3 Tremor 11 3 Pain Back 1 1 3 Headache 1 1 3 Headache 1 1 4

Summary of Results

D-methadone at the dose of 40 mg PO Q 12 hours was well tolerated inthis group of patients with chronic pain and multiple co morbidities,though further phase I and phase II studies may be needed to confirm itssafety and analgesic effects.

Since d-methadone is likely well tolerated at doses that provideclinically useful NMDA receptor antagonism, it is likely to be usefulfor the treatment of a wide spectrum of painful conditions.

Upon thorough review of the data from this study the inventorsdiscovered that patients taking d-methadone experienced: (1) Improvedwell-being: baseline 4.1—after treatment 2.9 (lower numbers indicateimproved mood): (2) Less anxiety: baseline 2.5—after treatment 1.5: and(3) Less tiredness: baseline 5.9—after treatment 3.6.

The above numbers indicate average scores for eight patients on VisualAnalogue Scales part of the Edmonton Symptom Assessment Score atbaseline and on day 12 of treatment with d-methadone 40 mg every 12hours.

These data signal possible therapeutic benefits from d-methadone for therelief of various psychological symptoms. These findings are enhanced byexcluding patients with baseline symptom scores insufficient to besusceptible to clinically relevant improvement. These findings did notcorrelate to changes in pain scores and, therefore, the presentinventors have determined that this suggests clinical indicationsindependent from analgesia.

These new findings, together with the experimental work performed bypresent inventor Charles Inturrisi [described in Gorman, A. L. et. al,“The d- and l-isomers of methadone bind to the non-competitive site onthe N-methyl-D-aspartate (NMDA) receptor in rat forebrain and spinalcord,” Neuroscience Letters, 223 (1997) pp. 5-8; Shimoyama, N. et. al,“d-methadone Is Antinociceptive in the Rat Formalin Test,” J Pharma andExper Therap, 293 (1997) pp. 648-652; Davis, A. M. and Inturrisi, C. E.,“d-methadone Blocks Morphine Tolerance and N-Methyl-D-Aspartate-InducedHyperalgesia,” J Pharma and Exper Therap, 289 (1999) pp. 1048-1053; andInturrisi, C. E., “Pharmacology of methadone and its isomers,” MinervaAnestesiol 71 (2005), pp. 435-437, incorporated by reference herein intheir entireties) and other literature cited in this application suggesta previously unrecognized benefit from d-methadone in many psychiatricsyndromes and symptoms. Further, the fact that d-methadone would bebeneficial in the treatment of psychiatric symptoms and conditionssuggests that similar drugs, such as d-methadol, d-alpha-acetylmethadol,l-alpha-acetylmethadol, d-alpha-normethadol, l-alpha-normethadol, andtheir pharmaceutically acceptable salts, would also be beneficial insuch treatment.

While the various aspects of the present invention have been disclosedby reference to the details of various embodiments of the invention, itis to be understood that the disclosure is intended as an illustrativerather than in a limiting sense, as it is contemplated thatmodifications will readily occur to those skilled in the art, within thespirit of the invention and the scope of the appended claims.

What is claimed is:
 1. A method of treating psychological andpsychiatric symptoms comprising: administering a composition to asubject suffering from one or more psychological symptoms chosen fromdepression, anxiety, fatigue, and mood instability includingpseudo-bulbar affect, the composition including, as the sole activeagent for treating said one or more psychological symptoms, an NMDAreceptor antagonist selected from d-methadone, d-methadol,d-alpha-acetylmethadol, d-alpha-normethadol, l-alpha-normethadol, andpharmaceutically acceptable salts thereof; wherein the NMDA receptorantagonist is isolated from its enantiomer or synthesized de novo; andwherein the administering of the composition occurs under conditionseffective for the NMDA receptor antagonist to bind to an NMDA receptorof the subject and thereby relieve the subject from said one or morepsychological symptoms.
 2. The method according to claim 1, wherein theNMDA receptor antagonist is d-methadone.
 3. The method according toclaim 2, wherein the NMDA receptor is capable of biological action, andwherein the administering is effective to block the biological action ofthe NMDA receptor.
 4. The method according to claim 2, wherein thesubject has a central nervous system, and wherein the NMDA receptor islocated in the central nervous system.
 5. The method according to claim4, wherein the subject is a mammal.
 6. The method according to claim 5,wherein the mammal is a human.
 7. The method according to claim 2,wherein the d-methadone in the form of a pharmaceutically acceptablesalt.
 8. The method according to claim 2, wherein the d-methadone isadministered intravenously.
 9. The method according to claim 2, whereinthe d-methadone is delivered at a total daily dosage of about 1 mg toabout 5,000 mg.
 10. A method of treating psychological and psychiatricsymptoms comprising: administering a composition to a subject sufferingfrom one or more psychological symptoms chosen from depression, anxiety,fatigue, and mood instability including pseudo-bulbar affect, thecomposition including, as the sole active agent for treating said one ormore psychological symptoms, an NE reuptake inhibitor selected fromd-methadone, d-methadol, d-alpha-acetylmethadol, d-alpha-normethadol,l-alpha-normethadol, and pharmaceutically acceptable salts thereof;wherein the NE reuptake inhibitor is isolated from its enantiomer orsynthesized de novo; and wherein the administering of the compositionoccurs under conditions effective for the NE reuptake inhibitor to bindto an NE receptor of the subject and thereby relieve the subject fromsaid one or more psychological symptoms.
 11. The method according toclaim 10, wherein the NE reuptake inhibitor is d-methadone.
 12. Themethod according to claim 11, wherein the NE receptor is capable ofbiological action, and wherein the administering is effective to inhibitNE reuptake at the NE receptor.
 13. The method according to claim 11,wherein the subject has a central nervous system, and wherein the NEreceptor is located in the central nervous system.
 14. The methodaccording to claim 13, wherein the subject is a mammal.
 15. The methodaccording to claim 14, wherein the mammal is a human.
 16. The methodaccording to claim 11, wherein the d-methadone in the form of apharmaceutically acceptable salt.
 17. The method according to claim 11,wherein the d-methadone is administered intravenously.
 18. The methodaccording to claim 11, wherein the d-methadone is delivered at a totaldaily dosage of about 1 mg to about 5,000 mg.